• Dating Wooden Beams from the Grancia Monastic Abbey in Southern Italy

      Gentilesca, T.; Todaro, L.; Ripullone, F.; Saracino, A.; Moretti, N.; Borghetti, M. (Tree Ring Society, 2016-01)
      We present the results of a dendrochronological study carried out on timbers from the monastic abbey Grancià of Brindisi di Montagna in Southern Italy. Our objective was to date cross-sections of oak (Quercus spp.) taken from structural timbers to determine the felling dates, the time span covered by the series and to evaluate whether the retrieved tree-ring data could be used to extend an existing living trees chronology of oak from Southern Italy. Dendrochronological analyses were performed on samples collected from eight oak timbers in 2006 during the restoration of the abbey. Raw tree-ring series were crossdated and grouped into a floating chronology that was compared with an absolute reference chronology, specifically constructed from living Quercus pubescens (Willd.) trees, from the nearby Pollino National Park. Seven of eight samples could be absolutely dated in the early 19th, late 18th and mid late 17th Centuries, providing a chronology that reaches back to AD 1545. © 2016 by The Tree-Ring Society.
    • Dendrochronology of Utah Juniper (Juniperus osteosperma (Torr.) Little)

      DeRose, R.J.; Bekker, M.F.; Kjelgren, R.; Buckley, B.M.; Speer, J.H.; Allen, E.B. (Tree Ring Society, 2016-01)
      Utah juniper was a foundational species for the discipline of dendrochronology, having been used in the early 20th Century investigations of Mesa Verde, but has been largely ignored by dendrochronologists since. Here we present dendrochronological investigations of Utah juniper core and cross-sectional samples from four sites in northern Utah. We demonstrate that, contrary to the general opinion among many dendrochronologists, Utah juniper exhibits excellent crossdating that is reflective of its sensitivity to climate-a desirable characteristic for dendroclimate reconstruction. Across all four sites the dominant signal for annual ring-width increment occurred during the growing season and was positive for precipitation and negative for temperature. This corroborates ecophysiological studies that highlight Utah juniper's aggressive water-use behavior and desiccation tolerance that together enable survival at extremely negative soil water potentials. This behavior differs from co-occurring Pinus spp. (i.e. P. edulis and P. monophylla) that avoid cavitation at the cost of carbon starvation. We determine that the annual radial increment of Utah juniper rings is particularly responsive to soil moisture availability, and is in fact a useful proxy for hydroclimatic variables such as precipitation, drought, and streamflow. Its geographic distribution spans a large swath of the Interior West, including areas where other more commonly sought-after species for dendrochronology do not occur, and ought to be considered crucial for complementing the rich network of tree-ring chronologies in the western U.S. © 2016 by The Tree-Ring Society.
    • Precipitation Variations in the Eastern Part of the Hexi Corridor during AD 1765-2010 Reveal Changing Precipitation Signal in Gansu

      Chen, F.; Yuan, Y.-J.; Zhang, R.-B.; Wang, H.-Q.; Shang, H.-M.; Zhang, T.-W.; Qin, L.; Fan, Z.-A. (Tree Ring Society, 2016-01)
      We reconstructed August-May precipitation from AD 1765 to 2010 for the eastern part of the Hexi Corridor, northwest China, using tree rings of Picea crassifolia. The precipitation reconstruction explains 44.1% of the actual precipitation variance during the common period of 1951-2010. The precipitation reconstruction is representative of precipitation conditions over a large area of the Hexi Corridor. Multi-taper spectral analysis reveals the existence of significant variability with periods of 9.3, 6.7, 3.1, and 2.6 years. Comparison between the precipitation reconstruction of the eastern part of the Hexi Corridor and other nearby precipitation/drought reconstructions shows high coherency in the timing of dry/wet episodes on annual to decadal scale. The divergences existing between the reconstructions may reflect the influence of different geographic features in Gansu and differences in seasonality of the various precipitation/drought reconstructions. © 2016 by The Tree-Ring Society.
    • The Benefit of Including Rarely-Used Species in Dendroclimatic Reconstructions: A Case Study Using Juglans nigra in South-Central Indiana, USA

      Maxwell, J.T. (Tree Ring Society, 2016-01)
      The benefit of using multiple species in dendroclimatic reconstructions in the eastern U.S. has been demonstrated. However, the benefit of including rarely-used species in multispecies reconstructions has been little explored. This paper shows the utility of using a rarely-used species in dendrochronology, Juglans nigra, in a multispecies Palmer Drought Severity Index (PDSI) reconstruction at a site in southern Indiana. First, the crossdating J. nigra is established, followed by determining the climate response. The standardized J. nigra chronology is then compared with co-occurring standardized species chronologies (Quercus alba, Quercus rubra, and Liriodendron tulipifera) reported in Maxwell et al. (2015). Using a principal component regression model, the bi-weights of each species were calculated to determine how much J. nigra contributed to the explanatory power of the model. J.nigra had a high interseries correlation (0.604) and mean sensitivity (0.304) and a strong correlation with summer PDSI, which was comparable in strength and more consistent through time than the cooccurring species. The inclusion of J. nigra in the composite reconstruction provided more consistency and better captured the observed PDSI variability. This is compelling evidence for why rarely-used species should be tested for inclusion in multispecies climate reconstructions. © 2016 by The Tree-Ring Society.
    • X-ray Densitometry of Norway Spruce Subfossil Wood from the Austrian Alps

      Klusek, M.; Grabner, M. (Tree Ring Society, 2016-01)
      The processing of subfossil wood poses some difficulties in densitometric research. Problems arise because of the physiochemical changes of wood occurring in the sedimentation environment. Subfossil wood modification can result from the uptake of mineral and organic substances into the wood tissue. It can also occur as the effect of microbiological degradation of wood. The goal of this study was to identify the appropriate method of subfossil wood preparation for the densitometric research. For this purpose the wood of Norway spruce from Lake Schwarzensee was subjected to extraction in deionized water, acetone and diluted acetic acid. The application of acetic acid did not significantly influence the density of the wood and acetone seemed to be too aggressive. The best result was obtained by rinsing the samples in cold de-ionized water. This extraction procedure allowed removal of unwanted water-soluble, organic and inorganic compounds from wood and simultaneously did not lead to the degradation of subfossil samples. © 2016 by The Tree-Ring Society.